The present invention relates to a filter apparatus for separating contaminant particles from a fluid stream and more particularly to a gaseous fibrous filter medium of variable density which can be selectively layered and adhesively treated in a unique and novel manner to be particularly assembled as a pocket type filter for extended life engine intake use.
Layered, adhesively treated, varying density engine inlet filters arranged in pocket form have been long known in the engine intake art and, in fact, several prior art patents were cited in the long since abandoned patent application, U.S. Ser. No. 561,884 applied for by joint inventors, Richard L. Smith and Robert W. Sexton, (copy enclosed) in the latter part of 1983 or early 1984. In this abandoned application, Examiner cited a number of references, four of which were considered to be particularly pertinent. GB patent No. 2,036,591, inventor Roy E. Cleaver published on Jul. 2, 1980 and U.S. Pat. No. 3,710,926 issued to Robert W. Sexton et al on Jan. 16, 1973, both teach multilayered fibrous filters. U.S. Pat. No. 3,201,926, issued to F. G. Harrington on Aug. 24, 1965 teaches the use of an adhesive coating impregnated in the filter fibers. Further U.S. Pat. No. 4,093,437, issued to H. Ichihara et al on Jun. 6, 1978, teaches a multilayered filter material of different densities, as does recently issued U.S. Pat. No. 5,496,627, issued to Shriram Bagrodia et al on Mar. 5, 1996.
Acknowledging that adhesively dispersed, multi-layered, different density fibrous filters in the form of open-mouth supported pocket members are known in the art, as taught by the above-noted several references, the present invention combines the several recognized features of the prior art in a unique, novel and inventive manner to provide a straightforward and economical filter apparatus which can be readily manufactured and maintained to provide a new and unexpected filter arrangement which is highly efficient with a comparatively high particulate separation and with a higher holding capacity at a given pressure drop without premature faceloading and filter media collapse. Further, in accordance with the novel filter structure of the present invention, during a gas treating operation, there is a reduction of downstream pressure drop without a corresponding reduction in particulate capturing and retention as a consequence of the unique increase of fiber density accompanied by a corresponding increase in adhesive quantity in planar sheet-like form, serving to provide a final means for particulate capture from the treated fluid stream. Thus, not only is the filtration efficiency greatly improved, but filtration life is greatly extended. Such high efficiency filtration with extended filter life has particular importance in the application of engine intake filters for locomotives, where the ordinary maintenance change-out period for a locomotive filter now can be increased two-fold without sacrifice of filtration efficiency and controlled pressure drop.
Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth herein.